Motor controlled automatic leveller circuit

ABSTRACT

An electrical circuit provides automatic levelling to maintain two movable bodies in the same relative positions with respect to each other. When the position of one body changes in a given plane, mechanical means are moved to actuate switching circuitry to restore the bodies to their original relative positions.

United States Patent Eggert, Jr. Sept. 5, 1972 [541 MOTOR CONTROLLEDAUTOMATIC [56] References Cited LEVELLER CIRCUIT UNITED STATES PATENTS[72] Inventor: Walter S. Eggert, Jr., l-luntmgdon Valley, Pa. 3,271,6509/1966 Riddle ..3l8/648 Assigneez Boothe Airside Services, Inc.1,996,055 4/1935 Boykow ..3l8/648 X [22] Filed: Jan. 28, 1971 PrimaryExaminer-T. E. Lynch [21] Appl. No: 110,432 Att0rney-Stowell &StowellRelated U.S. Application mm 57 ABSTRACT [63] Continuation-impart of Ser.Nos. 15,537, An electrical circuit provides automatic levelling to March2, 1970, Pat. No. 3,628,l l7, and Ser. maintain two movable bodies inthe same relative p 197()- positions with respect to each other. Whenthe position of one body changes in a given plane, mechanical U-S."318/648, means are moved to actuate witching circuitry to [51 Int...B64c restore the bodies to their original relative positions .[58]Field of Search ..318/648, 675

7 Claims, 3 Drawing Figures F1; /DOWN\ RELAY P'A'TE'N'TEDSEP 5 I972SHEET 1 UF 3 KOPOE 1N VENTOR.

WALTER S. EGGERT, JR. BY

ATTORNEY KATENTEDSEP- 1m SHEET 2 0F 3 mvENmR,

WALTER s. EGGERKJR.

ATTORNEY PATENTEDSEP 5 m2 3.689.822

SHEET .3 OF 3 INVEN TOR.

Y WALTER S. EGGERT, JR.

ATTORNEY filed, Mar. 2,1970 and Vertical Movement Sensor, Ser. No.76,346, filed Sept. 29, 1970.

In many situations, it is necessary to line up the floors .of twovehicles, for example, to permit transfer of material or passengers fromone vehicle to the other. It is desirable in these cases to have therelative positions of the .floor or platforms maintained in the sameplane to actuatethe circuit of FIG. 3, in accordance .withthe presentinvention, and

FIG. 3 is a schematic circuit diagram of aswitching arrangement whichmay be used with the devices illustrated in FIGS. 1 and 2.

Referring'to FIG,. 1, an automatic levellingsystem includes the sensingmeans movably mounted to a during the transfer operation. In many cases,the level of one of the-floors may vary slightly during the transferoperationasa result of different load conditions.

One such example wherein it is desirable to maintain the relativepositions of two bodies involves the use of a passenger transfer vehiclewhere passengers are transferred from thevehicle to an aircraft. Onesuch type vehicle is described in a U.S. Pat. No. 3,537,745 entitledAircraft Transfer Vehicle." In a vehicle of this type, passengers aretransferred from the vehicle onto an aircraft. During the loadingandunloading operation the relative levels of the floors of the transfervehicle and aircraft may vary because of the variations in loadconditions during the transfer operation. These variations in floorlevels, if not remedied, create hazardous conditions for passengersmoving to or from the vehicle and aircraft.

'It is desirable to automatically adjust the levels of the 'floors ofthe vehicle and/or aircraft to maintain them relatively constant duringtransfer operations.

It is an object of this invention to provide a novel electrical circuitand actuating means therefor for maintaining two movable bodiesinrelatively fixed relationship with respect to each other under varyingload conditions.

It is a further object ofthis invention to provide a novel system forrestoring .to predetermined relative positions two main bodies when oneof the bodies has moved beyond a predetermined distance with respect tothe other.

It is still a further object of this IIIVCHIIOI'IIO provide a novelsystem for restoring to predetermined relative positions two bodies whenone'of the bodies has moved beyond a predetermined distance with respectto the other wherein means are provided to vary said predetermineddistance.

In accordance with the present invention, a system for maintaining therelative position of a first body with respect to a second body includescam means movable in accordance with the relative movement between thefirst and second bodies to control the operation of switches. Motormeans are connected tothe switches to move and maintain the firstbody ina fixed relative position with respect to the second body after thebodies have moved beyond a .predetermined distance withrespect to eachother.

Other objects and advantages of the present invention will be apparentand suggest themselves to those skilled in the art, from -a reading ofthe following specification and claims, in conjunction with theaccompanying drawing, in which:

FIGS. 1 and 2 represent side views, partly broken .away and in crosssection, of two embodiments of mechanical sensing arrangements which maybe used vehicle 12. The vehicle -12 may be of the type for transportingpassengers between an airport terminalandan aircraft 14, such asdescribed in the aforementioned U.S. Pat. No. 3,537,745. I

In atypical situation, a driver of the vehicle l 2-brings it relativelyclose to the aircraft 14 and then adjusts the ramp or platform of thevehicle to a level corresponding to the level of the floor of theaircraft 14. Aspassengerspass from one vehicle to the other, the floorlevel of the vehicle .12 with respect to the floor level of the aircraft14 may move either up or down. The variations in floor levels may resultfrom the transfer of passengers, variations in loads between theaircraft and the vehicle, or for other reasons.

The assembly 16 including the sensing device .10 mounted thereon ismounted to a rail 18 .byany suitable means. The rail 18 is adapted tomove in and out on a plurality of rollers 20. The rollers20.aresecured-to a mounting plate 22 which in turn is secured to .thesidewall .23 of the vehicle 12. The entire assembly .16 including thesensing device 10, while illustrated in an .extended operativecondition, is normally .held retracted by a latch '24 when the vehicle12 is moving freeof the aircraft 14. Such latches are well known and thedetails thereof are not illustrated. I

After the vehicle 12 is moved within some predeter mined distance of theaircraft and the initial floor levelling between the two crafts isattained,,a'n operator releases the latch 24 making it possible forvtheoperator to-manually move the rail 18 over the rollers 20. Theoperator may then move theentire assembly outwardly so that anextendible member 26 is extended towards the aircraft 14. The extendiblemember 26 .includes an attachment assembly 28 for attachment to thesurface of the aircraft 14.

The attachment assembly 28, which forms partof the sensing means 10,includes a coupling member27 .having a fluid passageway 29 therein. Apair of suction cups 30 and 32 is mounted to the coupling member27 sothat the interiors of the suction cups are fluid coupledto thepassageway 29. The interior of thesuction cups are both thereforeconnected through the coupling member 27. A flexible hose 35 isconnectedto the coupling member 27 to connectthe passageway 29 to acompressor 34. The compressor 34 may be actuated by a switch 38. Whenthe compressor is operative,

exhaust pressure is created to evacuate the air within about thepivotpoint-40.

Changes in the relative positions between the aircraft l4 and thevehicle 12 cause the extendible element 26 to move up or down about thepivot point 37 depending upon the direction of relative movement betweenthe two bodies. However, despite changes in the relative positionsbetween the two bodies, the attachment assembly 28 carrying the suctioncups 30 and 32 are maintained in a fixed relationship with respect tothe plane 14. The assembly attachment 28 on the aircraft 14 may beconsidered the equivalent of a permanent mechanical mounting on theaircraft with means to permit the extendible element 26 to be pivotallyattached thereto.

The use of two suction cups instead of one provides advantages. Forexample, if a single suction cup were used on the end of the extendiblemember 26 and the two attached bodies were moved relative to each other,the single suction cup would be stressed with one portion of the cuptending to expand while another portion would tend to be compressed. Theresult would be a slight error in the sensing system. With a doublesuction cup arrangement, such as that illustrated, relative movementbetween the two bodies will not cause any flexing of the suction cupsthereby making possible a more accurate sensing system responsive solelyto the relative movement of the bodies.

Cam means include a plurality of cam elements 42, 44, 46 and 48 mountedto the member 36 by means of screws or other suitable means. The member36 is maintained in a neutral position by a spring loaded roller 38disposed within a groove in the member 36. The member 36 may includeslightly elongated holes 50 to permit the cam members 42, 44, 46 and 48to be mounted in slightly different positions with respect to eachother. After the cam members are mounted in the position desired, thescrews 51 associated therewith are tightened. Such adjustment screws arewell known to those skilled in the art and therefore not shown ordescribed in great detail. However, the means for adjusting thepositions of the cam elements slightly with respect to each otherprovide a feature of the present invention, as will be described inconnection with FIG. 3.

When the floor or ramp level of the vehicle 12 varies with respect tothe aircraft 14, the pivotable member 26 moves about its axis to actuatea plurality of switches which controls a motor to restore the originalrelative positions of the levels of the floors in the vehicle andaircraft.

The various cam elements 42, 44, 46 and 48 are adapted to actuate aplurality of switches 52, 54, 56 and 58, respectively. The switchesinclude a plurality of rollers 60, 62, 64 and 66, which are disposed tobe actuated by the various cam elements to open or close selectedswitches dependent upon the position of the pivotable element 26. Theswitches 52, 54, 56 and 58 may be paired with other switches to providea redundancy factor in the system. Also, the switches may be associatedwith additional contacts to provide a warning light to indicate faultyoperation, as will be described. These additional switches and contacts,while not illustrated in FIG. 1 are shown in the schematic diagram ofFIG. 3, to be described.

The switches 52, 54, 56 and 58 are connected to a cable 68 to controlvarious motor means 70 which may include up and down motors to controlthe up and down motion of the vehicle 12, as well as appropriate relays.Dependent upon the operating states of the various switches, the motormeans will remain in a neutral position or move the vehicle 12 up anddown. When the floor level of the vehicle 12 changes with respect to thefloor level of the aircraft 14, the motor means 70 will become operativeas a result of the actuation of selected switches to return the floorlevel of the vehicle 12 to its original position with respect to thefloor level of the aircraft 14.

In practicing the subject invention it is realized that certaintolerances must be set. For example, if the degree of movement of thefloor of the vehicle and aircraft is very slight or insignificant, themotor means 70 will not be operated. However, if the degree of movementis relatively great or beyond a predetermined limit, the motor means 70will become operative. This arrangement prevents jitter orover-sensitivity in the system which would tend to create a vibratingmovement of the floor of the vehicle. The spacing of the cam elementswhich control the operation of the switches determines the distance atwhich the restoring motor means 70 becomes operative.

Referring particularly to FIG. 2, a somewhat different arrangement forattaching the suction cups to the surface of an airplane 14 asillustrated. In this case, however, the extendible means 72 is notpivotable about a point on the vehicle 12. For purposes of clarity thecompressor and various elements for producing vacuum in the suction cups30 and 32 are not illustrated, it being understood that the samearrangement illustrated and described in connection with FIG. 1 may alsobe used with the arrangement of FIG. 2.

The suctions cups 30 and 32 are fixedly mounted to the end of theextendible element 72. An operator may manually extend the extendibleelement 72 through a plurality of rollers 74 until the suction cups 30and 32 are attached to the surface of the aircraft.

The rollers 74 are mounted to a plate 76. The plate 76 includes a pairof extending portions 78 and 80. The plate 76 and all parts associatedtherewith is adapted to be moved up and down and may be held normallycentered by biasing springs 81 and 83 fixedly mounted to the aircraft12.

The extending portion 78 is adapted to ride vertically up and down alongrollers 82 and 84. The extending portion is adapted to ride verticallyup and down along rollers 86 and 88. The entire plate member 76 isadapted to be moved up and down in accordance with the movement of theextendible portion 72.

When the extendible element 72 extends upwardly or downwardly, variousselected ones of the switches 90, 92, 94 and 96, associated with variousroller, are actuated by cam elements 91, 93, 95 and 97. The electricalcircuitry actuated by the arrangements of FIG. 1 and 2 is illustrated inFIG. 3.

Referring particularly to FIG. 3, the circuitry illustrated will berelated to the operation of the embodiment illustrated in FIG. 1, itbeing understood that it could also be related to the embodiment of FIG.2. First assume that the vehicle 12 is moved upwardly. In this case, thepivotable element 26 will be pivoted about the point 37 with the vacuumcups 30 and 32 maintain contact with the surface of the aircraft l4.

When the element 26 is pivoted in a counterclockwise direction, themember 36 is also turned to rotate the cam elements 42, 44, 46 and 48.Rotation of the cam'member 46 causes normally open switches 56 and 57 toclose. The double switch arrangement provides a redundnacy feature. Asmentioned, the switch 57 is not illustrated in FIG. 1. The closing ofthe switches 56 and 57 result from the roller 64 moving downwardly fromits peak position on the cam element 46. However, no activation of anyrestoring force takes place until the member 36 moves a predetermineddistance at which point the roller 66 rides up and contacts the topportion of the cam element 48. At this point, normally open switches 58and 59 are closed. Power is then applied from the terminals 71 and 73through the switches 56, 57,58 and 59 to the relay 72. The relay 72closes a pair of holding contacts 74. These contacts permit current toflow through the down relay 72 after the switches 58' and 59 aresubsequently opened.

The operation of the down relay 72 causes the motor means 70 to becomeoperative to cause the vehicle 12 to be moved downwardly. The downwardmovement of the vehicle 12 causes the pivotable element 26 to be rotatedin a clockwise direction starting it back to its original position. Whenthis happens, the roller 66 moves-downwardly from the upper portion ofthe cam element 48 to cause the switches 58 and 59 to open. However,since the roller 64 'has not yet reached its peak position on the camelement 46, the switches 56 and 57 will remain closed to keep the relay72 operative.

As the pivotable element 26 continues its clockwise rotation, the roller64 eventually reaches the peak of the cam element 46 causing theswitches 56 and 57 to open. At this point, the relay 72 becomesinoperative. The motor means 70 will also become inoperative and thesystem will be at its original or neutral position. It is noted thatwhile the switch 54 closes during the operation described, the switch 52remains open preventing the up relay 76 from operating.

Consider now a situation in which the vehicle 12 is moved downwardly.When this happens the pivotable element 26 is pivoted clockwise aboutthe pivot point 32. When the pivotable element 26 is moved in aclockwise direction, the roller 62 will move down from its peak positionon the cam element 44 to close the switches 54 and 55. Again, switch 55is not illustrated in FIG. 1, it being understood that the switch is inseries with the switch 54. The closing of the switches 54 and 55 doesnot affect the operation of the motor means 70 until the member 36 hasmoved beyond a predetermined distance. At this point, the roller 60rides up the cam element 42 to eventually close the normally openswitches 52 and 53. With all the switches 54, 55, 52 and 53 closed, anup relay 76 becomes operative to close a pair of holding contacts 77.

Operation of the relay 76 causes the motor means 70 to become operativeto move the vehicle 12 upwardly. This upward movement continues untilthe roller 60 rolls off the cam 42 to open the switches 52 and 53. Atthis point, the relay 76 continues to operate because the switches 54and 55 are still closed. After the movement has proceeded beyond apredetermined distance the roller 62 moves to the high portion of thecam element 44 to open the switches 54 and 55 thereby making the relay77 inoperative. At this point, the motor means becomes inoperative andthe system is restored to its original or equilibrium position. Duringthe up operation, the down relay 72 will not be affected because theswitches 58 and 59 will remain open since the roller 66 never rides upthe cam 48.

The various switches illustrated may include multiple contacts. Sets ofcontacts are provided in the switches which are normally closed andadapted to be opened when their counterparts are closed. For example, alight 78 may be operative in a vehicle when all the switches 52a to 59aare closed. This will indicate that the switchesare operating normallyprior to any operation of the vehicle 12. When any one of the switchesare defective or open, the light 78 will be out indicating some troublein the switching arrangement.

It is noted that the various cam elements 42, 44, 46 and 48 may beadjusted slightly to vary the distance necessary to operate the motormeans 70. This arrangement makes it possible to adjust the system sothat no operation will take place unless the positions of the floor ofthe vehicles have moved beyond a predetermined distance, for example,one inch.

The switching means may be considered as two sets of switches disposedto be sequentially operated. The first set becomes operative when thefloor of the vehicle moves from its neutral position with the second setbecoming operative at a limit point at which a restoring motor is to bemade operative. The restoring operation continues until the first set ofswitches is made inoperative.

While the circuitry of the subject invention has been described inconnection with a passenger transfer vehicle and an aircraft, it isapparent that its application may relate to any two bodies wherein it isdesired to restore their relative positions while various operations,such as varying loads, take place. Conceivably some elevator systemscould use the present invention.

Also, while the circuit has been described in connection with two bodieswhich are movable in a vertical plane, some situations may arise wherecorrections must be made when the bodies are movable in a horizontal orangular plane.

What is claimed is:

1. An electro-mechanical control assembly for maintaining the level of afirst body at a predetermined position relative to a movable second bodyof the type having a sensor and levelling controls mounted on the firstbody, characterized by:

an elongated extendible sensing member mounted on said first body andhaving a coupling member connected to the extended end of the sensingmember, said coupling member being adapted to be connected to themovable second body,

an operating member connected to the other end of said sensing member,

control means cooperating with said operating member, comprising a pairof up-switches and a pair of down-switches for sensing the movement ofthe second body,

each said pair of switches being connected in series and sequentiallyoperable to start a levelling motor, and

a hold circuit bypassing one of said switches in each said pair ofswitches whereby the other of said switches is solely operable to stopsaid levelling motor when said first body has been restored to saidpredetermined position relative to said second body.

2. An electro-mechanical control assembly as set forth in claim 1,wherein said control means comprises a plurality of spaced-apart camsset to sequentially operate said switches when said operating member ismoved by said sensing member.

3. An electro-mechanical control assembly as set forth in claim 1,wherein said cams are adjustably mounted on said operating member foradjustably setting the sequence of operation of said switches.

4. An electro-mechanical control assembly as set forth in claim 3,wherein said pair of up-switches and down-switches each include a doublepair of switch contacts, connected in series.

5. An electro-mechanical control assembly as set forth in claim 1,wherein said pair of up-switches and down-switches are each connected inseries with a relay which is operable to close their respective switchcontacts to operate the levelling motor.

6. An electro-mechanical control assembly as set forth in claim 5,wherein said hold circuit includes a pair of switch contacts operated byrelays.

7. An electro-mechanical control assembly as set forth in claim 6wherein said up-switches are connected in series with relay between apower source whereby said first switch is closed first, followed by theclosing of said second switch to energize said relay and start saidlevelling motor which operation then first opens said second switchfollowed by said first switch, to deenergize said relay and stop saidlevelling motor.

1. An electro-mechanical control assembly for maintaining the level of afirst body at a predetermined position relative to a movable second bodyof the tYpe having a sensor and levelling controls mounted on the firstbody, characterized by: an elongated extendible sensing member mountedon said first body and having a coupling member connected to theextended end of the sensing member, said coupling member being adaptedto be connected to the movable second body, an operating memberconnected to the other end of said sensing member, control meanscooperating with said operating member, comprising a pair of up-switchesand a pair of down-switches for sensing the movement of the second body,each said pair of switches being connected in series and sequentiallyoperable to start a levelling motor, and a hold circuit bypassing one ofsaid switches in each said pair of switches whereby the other of saidswitches is solely operable to stop said levelling motor when said firstbody has been restored to said predetermined position relative to saidsecond body.
 2. An electro-mechanical control assembly as set forth inclaim 1, wherein said control means comprises a plurality ofspaced-apart cams set to sequentially operate said switches when saidoperating member is moved by said sensing member.
 3. Anelectro-mechanical control assembly as set forth in claim 1, whereinsaid cams are adjustably mounted on said operating member for adjustablysetting the sequence of operation of said switches.
 4. Anelectro-mechanical control assembly as set forth in claim 3, whereinsaid pair of up-switches and down-switches each include a double pair ofswitch contacts, connected in series.
 5. An electro-mechanical controlassembly as set forth in claim 1, wherein said pair of up-switches anddown-switches are each connected in series with a relay which isoperable to close their respective switch contacts to operate thelevelling motor.
 6. An electro-mechanical control assembly as set forthin claim 5, wherein said hold circuit includes a pair of switch contactsoperated by relays.
 7. An electro-mechanical control assembly as setforth in claim 6 wherein said up-switches are connected in series withrelay between a power source whereby said first switch is closed first,followed by the closing of said second switch to energize said relay andstart said levelling motor which operation then first opens said secondswitch followed by said first switch, to de-energize said relay and stopsaid levelling motor.